1. Field of the Invention
The present invention relates to a key top switch for an electronic musical instrument such as an electronic piano, which is disposed in an operation panel of the electronic musical instrument as a versatile switch.
2. Description of the Prior Art
FIG. 1 illustrates an example of a conventional key top switch for an electronic piano equipped with a speaker (not shown). The key top switch 51 is disposed in an operation panel 52, for example, as a tone selection switch. The key top switch 51 comprises a switch board 53 made of a printed wiring board; and a large number of key tops 54 supported on the switch board 53. Each of the key tops 54, implemented by a molding made of synthetic resin, has a support 55 attached on the switch board 53; and a body 57 supported by the support 55 through a hinge 56. The support 55 has a top surface adhered to the back surface of the operation panel 52 with a double-sided adhesive tape 58. A pair of contacts 59 are formed on the surface of the switch board 53 and the lower surface of the body 57, respectively, such that they oppose each other.
As a player presses the body 57 of a key top 54 constructed as described above, the pair of contacts 59 are brought into contact to turn ON the key top 54. Responsively, the switch board 53 outputs an ON signal to a controller (not shown) to control the tone of the electronic piano. The top surface of the support 55 of the key top 54 adhered to the back surface of the operation panel 52 with the double-sided adhesive tape 58 prevents bouncing caused by relative vibrations between the operation panel 52 and key top 54 produced by acoustic vibrations generated from the speaker to limit noise.
FIG. 2 illustrates another example of a conventional key top switch for an electronic piano. The key top switch 60 is disposed in an operation panel 61, for example, as a tone selection switch, as is the case with the key top switch 51. The operation panel 61, made of an extrudate, comprises a large number of key top holes 62 extending therethrough in the vertical direction; and ribs 63, each of which protrudes at a predetermined position on the back side of the operation panel 61 and extending in the horizontal direction. The key top switch 60 comprises a switch board 64 in a similar structure to the switch board 53; and a large number of key tops 65 supported on the switch board 64 and slightly protruding from the key top holes 62 of the operation panel 61 associated therewith. Each of the key tops 65, which is a molding made of synthetic resin or the like, comprises a support 66 fitted on the rib 63 and attached to the switch board 64; and a body 67 supported by the support 66. The key top 65 is attached to the operation panel 61 with the support 66 fitted on the rib 63 of the operation panel 61, to position the key top 65 relative to the operation panel 61 at a predetermined position in the longitudinal direction. The key top 65 is positioned in the horizontal direction by adhering the top surface of the support 66 to the back surface of the operation panel 61 with a double-sided adhesive tape 58, while determining a position at which the key top 65 is attached through a visual check or the like, such that the center of the body 67 is aligned with the center of the key top hole 62.
Though not shown, the key top 65 is provided with a pair of positioning collapse sections protruding in the longitudinal direction at predetermined positions of the rib 63 in the horizontal direction for positioning of the key top 65 in the horizontal direction. The support 66 of the key top 65 is inserted between the positioning collapse sections to carry out the positioning. The positioning collapse sections are formed by pressing the rib 63 using a dedicated pressing die previously provided therefor.
However, in the conventional key top switch 51 illustrated in FIG. 1, the support 55 of the key top 54 must be adhered to the operation panel 52 using the double-sided adhesive tape 58 for preventing the key top 54 from bouncing. Since such a complicated operation must be performed for each of a large number of key tops 54, the key top switch 51 suffers from an increased manufacturing cost.
The conventional key top switch 60 illustrated in FIG. 2, in turn, implies the following problems. When the key top 65 is positioned relative to the operation panel 61 in the horizontal direction using the double-sided adhesive tape 58, each of a large number of key tops 65 must be adhered while determining a position at which the key top 65 is attached. This adhering operation is very complicated, causing an increase in the manufacturing cost of the key top switch 60. Also, since the human""s vision is relied on to determine the position at which the key top 65 is attached, the position cannot be accurately determined in some cases. Even if the position is accurately determined, it is difficult to precisely adhere the key top 65 at that position, thereby failing to provide a high accuracy for the attachment and a uniform quality.
On the other hand, when the key top 65 is positioned in the horizontal direction using the positioning collapse sections formed on the rib 63 of the operation panel 61, it is technically difficult to form the positioning collapse sections with a high accuracy through pressing. In addition, the aforementioned pressing die is required for forming the positioning collapse sections. However, the fabrication of such an expensive pressing die only for purposes of positioning causes a large costly burden and a resulting increase in the manufacturing cost of the key top switch.
The present invention has been made to solve the problems as mentioned above, and it is an object of the invention to provide a key top switch for an electronic musical instrument which is capable of preventing noise due to bouncing between an operation panel and a key top, and permitting accurate and easy positioning of the key top at a predetermined position in the longitudinal direction and horizontal direction of the operation panel, and can be manufactured at a low cost.
To achieve the above object, according to a first aspect of the present invention, there is provided a key top switch for an electronic musical instrument disposed in an operation panel thereof, which is characterized by comprising a switch board attached on a back side of the operation panel; and a key top sandwiched between the operation panel and the switch board, and including a contact member in contact with the switch board, and a resilient arm for urging the contact member toward the switch board.
In this key top switch for an electronic musical instrument, the key top is sandwiched between the operation panel and the back side of the switch board, and the contact member of the key top is in contact with the switch board, and urged by the resilient arm of the key top toward the switch board. Since the key top is pressed against the switch board through the urged contact member at all times, the key top is prevented from vibrating with respect to the operation panel due to acoustic vibrations generated from a speaker. Consequently, it is possible to prevent bouncing between the key top and operation panel and noise caused thereby. Thus, unlike the conventional key top switch, the attachment of the key top to the operation panel can be simplified by omitting the adhesion of the key top with a double-sided adhesive tape for preventing noise, thereby reducing the manufacturing cost of the key top switch.
According to a second aspect of the present invention, there is provided a key top switch for an electronic musical instrument disposed in an operation panel thereof. The operation panel has a rib protruding on a back side thereof and tapered toward its leading end. The key top switch is characterized by comprising a switch board attached on the back side of the operation panel; and a key top sandwiched between the operation panel and the switch board, and including a contact member which is in engagement with the rib and is in contact with the switch board.
According to this key top switch for an electronic musical instrument, the key top is sandwiched between the operation panel and the switch board, and the contact member of the key top is in contact with the switch board, and is in engagement with the rib. Since this rib protrudes on the back side of the operation panel and is tapered toward its leading end, a force acts on the contact member engaging with the rib thus formed to come off the rib. Since the key top is pressed against the switch board through the contact member at all times by this action, the key top is prevented from vibrating with respect to the operation panel due to acoustic vibrations generated from a speaker. Consequently, it is possible to prevent bouncing between the key top and operation panel and noise caused thereby, as is the case with the first aspect. In addition, the manufacturing cost of the key top switch can be reduced by omitting the adhesion of the key top with a double-sided adhesive tape for preventing noise.
Preferably, in the key top switch for an electronic musical instrument, the key top further comprises a resilient arm for urging the contact member toward the switch board.
According to this preferred embodiment of the key top switch, since the contact member of the key top is in contact with the switch board with an urging force acting thereon from the resilient arm, in addition to the pressing force from the rib, it is possible to more securely prevent the bouncing between the operation panel and key top and noise caused thereby.
According to a third aspect of the present invention, there is provided a key top switch for an electronic musical instrument disposed in an operation panel thereof. The operation panel has a rib formed at a predetermined position in a longitudinal direction on the back of the operation panel for positioning in the longitudinal direction. The key top switch is characterized by comprising a key top having a first and a second engagement member, and attached on the operation panel with the first engagement member in engagement to the rib; and a switch board having an engagement member at a predetermined position in a horizontal direction for positioning in the horizontal direction, and fixed to the operation panel with the engagement member in engagement to the second engagement member of the key top.
According to this key top switch for an electronic musical instrument, the key top is attached on the operation panel with its first engagement member in engagement to the rib for positioning in the longitudinal direction. Since the rib for positioning is disposed at a predetermined position in the longitudinal direction of the operation panel, the key top can be accurately and readily positioned at a predetermined position in the longitudinal direction of the operation panel. The switch board is fixed on the operation panel with its engagement member for positioning in the horizontal direction in engagement to the second engagement member of the key top. Since this engagement member for positioning is disposed at a predetermined position in the horizontal direction of the switch board, the key top can be accurately and readily positioned at a predetermined position in the horizontal direction of the operation panel through the switch board. As a result, unlike the conventional key top switch, the attachment of the key top to the operation panel can be simplified by eliminating the adhesion of the key top with a double-sided adhesive tape for positioning in the horizontal direction, and the collapsing of a rib for forming positioning collapse sections, thereby reducing the manufacturing cost of the key top switch.